From eea569fa3a644e7a0156420365799f7eaa88a3c4 Mon Sep 17 00:00:00 2001
From: Erez Shinan <erezshin+git@gmail.com>
Date: Thu, 16 Nov 2017 19:59:34 +0200
Subject: [PATCH] Tiny fix

---
 lark/parsers/earley.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lark/parsers/earley.py b/lark/parsers/earley.py
index 3c04ac1..f90c000 100644
--- a/lark/parsers/earley.py
+++ b/lark/parsers/earley.py
@@ -114,8 +114,8 @@ class Column:
                 if item.rule.expansion and item_key in self.completed:
                     old_tree = self.completed[item_key].tree
                     if old_tree == item.tree:
-                        is_empty = len(self.FIRST[item.rule.origin])
-                        if is_empty:
+                        is_empty = not self.FIRST[item.rule.origin]
+                        if not is_empty:
                             continue
 
                     if old_tree.data != '_ambig':